逻辑结构

regs1[i] = regs1[0]+regs1[1] + … + regs1[i-1] + regs2[0]+regs2[1] + … + regs21[i-1]
regs2[i] = regs1[0]+regs1[1] + … + regs1[i-1] + regs2[0]+regs2[1] + … + regs21[i-1] +regs1[i]
看似复杂，主要为了可以制造出违例。

代码

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
typedef logic [255:0] l256;
parameter times = 5;
module dut(
    input clk1,
    input clk2,
    input rstn,
    input l256 in,
    output logic out
);
    l256 regs1 [times]; 
    l256 regs2 [times]; 

    logic clk_xor;
    logic rstn_sync1, rstn_sync;
    l256 tmp_regs; 

    XOR2X1AS9 u_xor(.O(clk_xor),.I1(clk1),.I2(clk2));

    always@(posedge clk_xor or negedge rstn)
    if (!rstn) begin
       rstn_sync1 <= 1'b0; 
       rstn_sync <= 1'b0; 
    end
    else begin
       rstn_sync1 <= 1'b1; 
       rstn_sync <= rstn_sync1; 
    end

    always@(posedge clk_xor or negedge rstn_sync)
    if(!rstn_sync) begin
        for (int i = 0; i<times; i++) begin
        regs1[i] <= {256{1'b0}};
        regs2[i] <= {256{1'b0}};
        end
    end
    else begin
        for(int i=0;i<times; i++) begin
            tmp_regs = 0;
            if(i==0 ) begin
               regs1[i] <= in;
               regs2[i] <= regs1[i];
            end
            else begin
               for(int j=1; j<i;j++)
                  tmp_regs = tmp_regs + regs1[j] + regs2[j];
               regs1[i] <= tmp_regs; 
               regs2[i] <= tmp_regs + regs1[i]; 
            end
        end
    end

    always@(posedge clk_xor or negedge rstn_sync)
    if(!rstn_sync) 
        out <= 1'b0;
    else
        out <= ^{regs1[times-1],regs2[times-1]};  // 256 + 256 

endmodule

以上为可综合代码。注意tmp_regs = 阻塞赋值。

综合脚本

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
sh  mkdir -p    ./work
define_design_lib WORK -path ./work
set_host_options -max_cores 8

set search_path ./
lappend search_path xxx/ccs_db
set             synthetic_library [list dw_foundation.sldb] 
set target_library xxx_ccs.db
set link_library "* dw_foundation.sldb $target_library"

set_svf dut.svf
analyze -work WORK -format sverilog non_unate_clocks.sv
elaborate dut -work WORK -update
link

current_design dut
set_dont_touch [get_cells u_xor]

create_clock -name clk1 [get_ports clk1] -period 5
create_clock -name clk2 [get_ports clk2] -period 4

create_generated_clock -name clk1_xor [get_pins u_xor/Z] -source  [get_ports clk1] 
   -master clk1 -divide_by 1 -combinational -add
create_generated_clock -name clk2_xor [get_pins u_xor/Z] -source  [get_ports clk2] 
   -master clk2 -divide_by 1 -combinational -add

compile

return

分析

分析1

Clock Period Waveform Attrs Sources

clk1 5.00 {0 2.5} {clk1}

clk2 4.00 {0 2} {clk2}

Warning: A non-unate path in clock network for clock ‘clk1’
from pin ‘u_xor/O’ is detected. (TIM-052)
Warning: A non-unate path in clock network for clock ‘clk2’
from pin ‘u_xor/O’ is detected. (TIM-052)

违例1
Point Incr Path
clock clk2’ (rise edge) 2.00 2.00
clock network delay (ideal) 0.00 2.00
regs2_reg[3][27]/CK (DFFRBQX1AS9) 0.00 # 2.00 r
regs2_reg[3][27]/Q (DFFRBQX1AS9) 0.19 2.19 f
add_1_root_add_0_root_add_45_2_I3_I5/A[27] (dut_DW01_add_J4_0)
0.00 2.19 f
regs2_reg[4][209]/D (DFFRBQX1AS9) 0.00 4.88 f
data arrival time 4.88

clock clk1’ (rise edge) 2.50 2.50
clock network delay (ideal) 0.00 2.50
regs2_reg[4][209]/CK (DFFRBQX1AS9) 0.00 2.50 r
library setup time -0.06 2.44
data required time 2.44
data required time 2.44
data arrival time -4.88
slack (VIOLATED) -2.44

首先clk2到clk1，不合理。

设置如下

1
2
set_clock_groups -name clk1_clk2 -logically_exclusive -group {clk1} -group {clk2}

分析2

Point Incr Path
clock clk1’ (rise edge) 2.50 2.50
clock network delay (ideal) 0.00 2.50
regs2_reg[3][27]/CK (DFFRBQX1AS9) 0.00 # 2.50 r
regs2_reg[3][27]/Q (DFFRBQX1AS9) 0.19 2.69 f
add_1_root_add_0_root_add_45_2_I3_I5/A[27] (dut_DW01_add_J4_0)
regs2_reg[4][209]/D (DFFRBQX1AS9) 0.00 5.38 f
data arrival time 5.38

clock clk1 (rise edge) 5.00 5.00
clock network delay (ideal) 0.00 5.00
regs2_reg[4][209]/CK (DFFRBQX1AS9) 0.00 5.00 r
library setup time -0.06 4.94
data required time 4.94
data required time 4.94
data arrival time -5.38
slack (VIOLATED) -0.44

已经排除了clk1 , clk2之间的错误检查。但是因为non-unate，所以clk1’（即 clk1的反向时钟），会检查clk1，这也是不合理的。
有两个点
（1）non-unate时，timing还是会检查的，
（2）可能不合理，主要是更加严格了。

分析3

先对clk1进行纠正

1
2
set_sense -type clock -positive -clocks {clk1} [get_pins u_xor/O]

Point Incr Path
clock clk1 (rise edge) 0.00 0.00
clock network delay (ideal) 0.00 0.00
regs2_reg[3][27]/CK (DFFRBQX1AS9) 0.00 # 0.00 r
regs2_reg[3][27]/Q (DFFRBQX1AS9) 0.19 0.19 f
regs2_reg[4][209]/D (DFFRBQX1AS9) 0.00 2.88 f
data arrival time 2.88

clock clk1 (rise edge) 5.00 5.00
clock network delay (ideal) 0.00 5.00
regs2_reg[4][209]/CK (DFFRBQX1AS9) 0.00 5.00 r
library setup time -0.06 4.94
data required time 4.94
data required time 4.94
data arrival time -2.88
slack (MET) 2.06

但是clk2还是有问题
Point Incr Path
clock clk2 (rise edge) 0.00 0.00
clock network delay (ideal) 0.00 0.00
regs2_reg[3][27]/CK (DFFRBQX1AS9) 0.00 # 0.00 r
regs2_reg[3][27]/Q (DFFRBQX1AS9) 0.19 0.19 f
add_1_root_add_0_root_add_45_2_I3_I5/A[27] (dut_DW01_add_J4_0)
0.00 0.19 f
clock clk2’ (rise edge) 2.00 2.00
clock network delay (ideal) 0.00 2.00
regs2_reg[4][209]/CK (DFFRBQX1AS9) 0.00 2.00 r
library setup time -0.06 1.94
data required time 1.94
data required time 1.94
data arrival time -2.88
slack (VIOLATED) -0.94

分析4

对clk2进行纠正

1
2
set_sense -type clock -positive -clocks {clk2} [get_pins u_xor/O]

regs2_reg[4][209]/D (DFFRBQX1AS9) 0.00 2.88 f
data arrival time 2.88

clock clk2 (rise edge) 4.00 4.00
clock network delay (ideal) 0.00 4.00
regs2_reg[4][209]/CK (DFFRBQX1AS9) 0.00 4.00 r
library setup time -0.06 3.94
data required time 3.94
data required time 3.94
data arrival time -2.88
slack (MET) 1.06

最后

以上就是羞涩柜子最近收集整理的关于non-unate clock通过DC综合工具演示逻辑结构代码分析的全部内容，更多相关non-unate内容请搜索靠谱客的其他文章。